UPDATE 1-Soccer-Rebel clubs plan breakaway North American league

* Rebel clubs plan to start their own competition

* Officials say they will oppose breakaway plans

(Adds USL reaction)

By Simon Evans

MIAMI, Nov 10 (Reuters) - North America will have a new soccer league from April after rebel clubs broke away from the established second tier league to form a new competition.

The seven clubs, previously tied to the United Soccer Leagues (USL), the structure below Major League Soccer, said on Tuesday they had formed a new league and begun the formal process of gaining official recognition from governing bodies.

The seven include USL champions Montreal Impact and the team they beat in the league's final game -- Vancouver Whitecaps.

The Carolina Railhawks, Miami FC and Minnesota Thunder have also split from USL to form the new league along with former USL team the Atlanta Silverbacks and a new team from St. Louis.

A statement from the clubs said they were already in talks with other prospective teams about joining the league.